Earth Through Time

Question 1

What is the geologic time scale, and what types of evidence allow scientists to update it?

Answer 1

The geologic time scale is used organize Earth’s long history into manageable parts

Question 2

Divisions of the Geologic Time Scale:

Answer 2

Eons
Eras
Periods
Epochs

Question 3

How do scientists determine the end of one era and the beginning of another?

Answer 3

A mass extinction or massive explosion
A basically death or the blooming of life

Question 4

The deeper the sedimentary rock layer, the_______

Answer 4

older the rock is

Question 5

Fossil:

Answer 5

traces or remains of an organism that lived long ago

Question 6

Index Fossil:

Answer 6

remains of an organism that was common but only existed for a short time

Question 7

What is relative age?

Answer 7

Relative age is how old something is compared to how old something else is

Question 8

What is absolute age?

Answer 8

Absolute age identifies how old an objects is, as expressed in units of time.

Question 9

What is relative dating?

Answer 9

Relative dating is method used to determine whether something is older or younger than something else.
Scientists use the rock record.

Question 10

What is absolute dating?

Answer 10

Absolute dating is a method of measuring the actual age of something in year.
All rocks have uranium
The older it gets the less uranium and the more lead

Question 11

How scientists determine the absolute age of Earth?

Answer 11

Scientists find the absolute age by looking at present of uranium and percent of lead scientists check how old meteorites are.

Question 12

Where are the older fossils going to be found in sedimentary rock layer?

Answer 12

The deeper the sedimentary rock layer, the older the rock is.

Question 13

What is a fossil? What is an index fossil?

Answer 13

A fossil is the trace or remains of an organism that lived long ago.